Optic neuritis and the risk of multiple sclerosis—what can we learn from a brain MRI scan?

Abstract

In the Optic Neuritis Study Group's 15-year final follow-up, the cumulative probability for developing multiple sclerosis (MS) after a first episode of optic neuritis was 50%, with the risk highest in the first 5 years. If the MRI was negative at baseline, the risk of MS was 25% overall, and much lower for males and those with atypical presentations of optic neuritis. A single lesion doubled the 15-year risk to 50%. The risk associated with three or more lesions was 78%. However, the conclusion that “even a single lesion more than doubles the future risk of MS” must be interpreted with caution when using the latest imaging technology—the baseline MRI scans in this study were performed before availability of gadolinium enhancement and advanced inversion recovery imaging. The 32% conversion rate to MS between years 10 and 15 for patients with a positive baseline scan suggests that patients should be followed up for longer in order to further define the natural history of the disease.